Telephone system.



F. M. SLOUGH, TELEPHONE SYSTEM. AiPPLlCATION FILED NOV. 12. 19M.

Patented Oct. 29, 1918.

2 SHEETS-SHEEI I.

INVENTOR' 6101/ /2 JM AT M m m v WITNESSES Ed Fh l@,

FRANK M. SLOUGI'I, OF ELYRIA, OHIO, ASSIGNOR, BY MESNE ASSIGNMENTS, TO STROMBERG-CARL$ON TELEPHONE 00., OF ROCHESTER, NEW YORK, A

CORPORATION OF NEW YORK.

TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Oct. 29, MM 8%,

Application filed November 12, 1914. Serial No. 871,666.

To all whom it may concern:

Be it known that I, FRANK M. SLoUGH, a citizen of the United States, residing at Elyria, in the county of Lorain and Stateof Ohio, have invented certain new and useful Improvements in Telephone Systems; and I do hereby declare the following to be a full, clear, and eXact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same. y

My invention relates to improvements in telephone systems, and especially to improvements in What are known as automatic ringing systems, in which means are provided for continuing ,the ringing of the subscriber, after it has once been started by the operator, until the subscriber responds, when it is automatically disconnected through agencies under the control of the subscriber. In systems of this kind heretofore in use, so far as I am aware, the disconnect apparatus has been made such that it would respond to the substation signal operating current if the conditions happen to be right. For example, in the strength of current systems which are those almost universally in use, so far as I am aware, the disconnect apparatus has been operated by increasing the flow of current in the line, for example, by substituting a low resistance talking set for the high resistance bell bridge, and thereby increasing the strength of the current, so that the disconnect device would operate, Whereas it hadrefused to respond to the strength of current flowing before the low resistance bridge was placed upon the line. If, however, connection were made to a line upon which were a number of substations, the impedance ofiered to the flow of alternating current or signal operating current would be so reduced according to a well known law of electricity, that the flow of current would now be sufficient to operate the disconnect device just as effectively as if the subscriber had responded. Therefore, the first impulse of ringing current would disconnect the ringing current and the desired subscriber would never be rung.

, Frequently, also, the conditions of a line are such that less current will flow over the same when the receiver is off the hook than will flow over a short line when the receiver is on the hook. For example, sometimes the impedance of a long line with the receiver removed and the low resistance bridge completed, will be greater than that of a short line with the low resistance bridge broken and the relatively high resistance path completed. The central station apparatus being so adjusted as to respond to the strength of current flowing over the long line when the receiver is off the hook, will the more readily respond to the flow of current over the short line when the receiver is on the hook, so that the disconnect apparatus will workas soon as the ringing starts and the desired subscriber on the short line will never be rung. Owing to this and other objections to the present systems of automatic ringing in vogue, considerable limitation has been placed upon the use of the same, and the operating companies employing the same have been handicapped, especially where longcountry'lines and short city lines center in the same exchange. This trouble has also been keenly felt where multi-party lines have been employed, and as these conditions of long and short lines, some of which are multi-party lines, are employed in practically all exchanges, the automatic ringing hitherto used has had its limitations.

Efforts have also been made, so I am informed, to cure these defects, one of which .flow, at the same time being sensitive to direct current flow. Such expedients have failed largely because of the fact that such a relay is composed in part of a normally open magnetic circuit, and is, therefore inefficient a transformer, particularly to alternating currents of commercial frequencies used for the purpose of ringing tele phone bells. Therefore, only a portion of the alternating current pulsations would be subdued by the copper band. the balance being sometimes suiiicient to cause the operation of the relay. Such systems have been subject to the same defects heretofore described, in that if a sufiicient number of substations were upon the line, or if for other reasons the resistance or impedance of the line to the ringing current was suiticiently reduced, the specially constructed relay would intermittently respond. Others have sought to remedy the defect by excluding the bulk of the ringing current from that portion of the ringing circuit wlnch controlled the cut-off controlling device, but

these systems have likewise failed, because it is next to impossible to exclude all of the ringing current and at the same time enable the subscriber at all times to control the cut-off device, and if the system was so constructed that-little or none of theringing for certain lines they would operate improperly, and as such lines are always met with in practice sooner or later, these systems have been defective.

Needless to say, numerous other etlorts have been made to improve the system so as to make it meet all the conditions of practice, but so far as I am aware, this has not been done.

The object of my invention is to overcome these obstacles and to produce a cut-oil device which will under no circumstances respond to the ringing current at all until the subscriber has responded. In accomplishing these, I wipe out all of the delicate adjustments, strength of current, marginal schemes, mechanisms for preventing the cutoil controlling apparatus from responding to fluctuating currents and other such del cate mechanisms, and provide a cut-ofi controlling mechanism which responds to the alternating current or not. My success lies in providing a cut-off mechanism which will not respond, even though its controlling mechanism is responsive to fluctuating currents. I further provide means controlled by the subscriber for causing the operation of the cut-oil mechanism and a cut-off mechanism which will not respond until the subscriber starts the same into operation.

Other. objects of myinvention and the invention itself will probably be better understood from a description of particular embodiments.

Figure 1 is an illustration of the prefer-red embodiment of my invention.

Fig. 2 is a diagrammatic illustration of a modification of Fig. 1.

l ig. 3 is a diagrammatic illustration of electric current and magnetic flux curves.

Referring now to the embodiment illustrated in Fig. 1, at I is shown a telephone line which may be here spoken of properly as the calhng line, and which I have for conductors 8 and 9 to the main station.

The line II is provided vith a plurality of substations, A A A A, Each is provided with bells B B B 13,, which are included in the telephone apparatus. This apparatus also includes receivers C C C C transmitters D 1),, I),, D, and switch hooks E 13 ,1 1,, E,. Condensers may likewise be connected in the bell bridges.

I have illustrated'a third telephone line, shown at IV which-may also be called a called line. This line is provided with sub station apparatus A, which includes a bell 13,, a receiver G a transmitter D and a switch hook The line II leads by its line limbs or conductors 10 and 11 to the main station and the line IV leads by its line limbs or conductors 13 and 1'-l to the main station. At the main station means are provided for connecting the telephone lines together, here shown as a cord circuit, which consists of a plurality of strands including talkingstrands 15 and 16. Switching apparatus is provided for connecting the cord circuit to the telephone lines, here shown as plugs and jacks, the line I being provided with a jack J, the line II with jacks J and J and the lineIV with jacks J and J The cord is provided'with an answering plug P and a calling plug P Of course the lines may be provided with any suitable number of jacks. Each line is also provided with line signals, the line I with the line signal L,,-the line II with the line signal L and the line IV with the line signal I Each line is also P ovided with line relays, the line I with the line relay G the line II with the linelrelay G, and the line IV with the line relay G,. Each line is also provided with cutoff relays, the lines I, II and IV being provided with the cut-off relays Hi, H and H respectively. The

cord circuit is provided with suitable superf visory signaling apparatus, the answering end of the cord being provided with a super visory lamp L and the calling end of the cord being provided with a supervisory lamp L These lamps are controlled by supervisory relays K, K for the lamp L and K and K for the lamp L Means are provided for operating the signal bells B, 13 ,13 13 B,, B In the form shown these means are located at the main station and are illustrated as alternating current generators M, M M M I have-illustrated in diagrams the apparatus which is employed in the well known harmonic selective signaling systems, in which four parties are generally employed, it being understood that I am not limited to a four party-line, but contemplate lines on which any number of subscribers may be connected. Of course, where but one subscriber is connected but one generator is necessary. In this well known harmonic system each generator is adapted to produce an alternating current of a certain definite frequency and the bells at the substations respond one to each of these frequencies. This arrangement, however, may be employed without departing from the spirit of my invention. Means are provided for connecting one of the gen erators to the bell of the desiredsubscriber, in order that the bell may be operatedby the current supplied by the generator. In the form shown this connection is effected through conductors, switches, a portion of the cord circuit, the apparatus for connecting the cord to-the lines and the telephone line. In the form shown I provide'means for breaking up the ringing current into inter vals, so that the subscribers bell may be rung at intervals, avoiding an incessant ringing of the bell. These means'are shown as commutators N, N N N which rotate constantly, alternately making and breaking the circuit of the ringing circuit. At 0, 0,, 0-,, O are shown switches, here illustrated as manual switches controlling the connection of the generating means to the signal bell, one key being provided for each generator. 7

At Q, Q Q and Q Ishow relays which are controlled by the keys 0, 0,, O 0,, which in turn control the connection of the generators to the lines. AtR is shown a relay which controls the talking strands of the cord circuit and the connection of the ringing current to the telephone line. At S is shown a relay preferably made slow acting, as illustrated in the embodiment shown in Fig. 1 and which controls the disconnection of the rmging current from the telephone magnet flux; is constant or substantially unidirectional, the switch 20, -21 is closed and whichever one of the relays' Q, Q,,

or Q, has been operated, will be deenergized and the connection between the ringing generator and the bell interrupted. The char acter of the current whichflows through the relay S may be changed in a number of ways and the character of the flux in the relay S may be changed in a number of ways to effect the functions which it is to perform. In the form shown I have accomplished this changeby superposing upon the alternating current produced by the generator a direct current, which upon the response of the called subscriber, will cause a resultant current of a different character. In the embodiment illustrated in Fig. l the wave form will be changed with respect to the line of Zero polarity. lVhile the unmodified alternating current was flowing, the flux in the circuit of the relay S would be of alternating polarity, following the alternating current. However, when the current is shifted, its flux will be substantially constant, or of substantially unidirectional polarity, and the magnet will be operated for a suilicient length of time to cause the disconnection. However, when the alternating current alone is applied, the switch 2021 will be closed for such brief-intervals of time that the magnet Q will never let go its contacts.

The operation of the system illustrated in Fig. l is as follows: Assuming that the subscriber at A desires to communicate with the subscriber at A the receiver 0 is removed from the switch hook E, closingthe switch E22 and completing a circuit through the line relay G causing the illumination of the line lamp L This lamp is located so that it will attract the attention of the operator, who will insert the plug P into the ack J and in the well known manner learn that it is the subscriber at A, that is wanted. She then inserts the plug P into one of the jacks J, and depresses one of the ringing keys, according to what character of current is clesired. Assuming that the generator M prc duces the character of current desired, the key 0 would be depressed, completing a circuit as follows: ground at 23contact 24-- Orelay Qconductor 25-relay R-conductor 26--27--2829303132 3- 3-t-battery 85to ground at 36, energizing the relays Q and R, the relay K having previously been energized in the well known way when the plug P was inserted into the jack J through a circuit including theanswering end of the cord and the calling line. 40 and 4-1, completing a locking circuit for the relay Q through 4:0 l-2 to ground at The attraction of the armature 4C1 closes a switch .41 i l in the ringing circuit. The relay It attracts its armatures 45 and 46, interrupting the talking strands of the cord circuit and closing the switches 4l5-l7 and t6l8 in the ringing circuit. The ringing The relay Q, willattract its armatures the relay S will rapidly energize and deedergize the same in such a manner that the switch 2021 will be closed, it at all, only for short intervals of time. The periods for which this switch will be closed, it at all, will be functional to the frequency of the ringing current employed. The intervals of closure of this switch during the ringing period will be so slight thatthe shunting effect of the instantaneously closed switch 20-21 on the magnet Q will. be ineffective to deenergize the relay Q, owing to the fact that the magnetism in a short-circuited relay decays very slowly. All during the ringing period, the condenser (32" at substation A prevents the flow of direct current from the battery 60.

When the subscriberresponds, the switch E -(t3 will be closed, owing to theremoval oi the receiver C, from thehook E which may be spring pressed upward. This will shunt the condenser 62 and admit the flow of direct current from the source 60. As a result, a different kind of current will flow in the circuit, including the relay S, and as a result thereof the relay S will operate. In. the i'ornrshown the current flowing in the circuit of the relay S, after the receiver is removed from the hook, will be an alternating current, which is shifted with respect to the zero abscissa, orit may be a pulsating current, according to the relative strength of the alternating and direct currents. his current will cause a substantially constant, or substantially undirectional, flux to flow in the magnet S. The magnet of the relay S will not be energized for a suflicient length of time to hold steadily closed the switch 2021 long enough to effectively shunt the magnet Q which will be deenergized, whereupon the armature ll drops back, opening the ringing circuit at IL-let and disconnecting the generator from the signal bell. At the same time, the circuit of the relay R will be broken, still further interrupting the ringing circuit and restoring the cord circuit. The subscribers will then be in connection and at the termination of the conversation, the operator will be apprised of the desire for the disconnect, and the plugs will be withdrawn, restoring the system to normal.

In the form shown in Fig. 2, the relay It, has been made slow acting in any suitable manner, such as by providing it with a copper collar 100. The circuit of this relay is controlled by the relay S, and when the relay S is actuated by the alternating current,

flow of alternating current during the ringing period. The curve Y represents the direct current introduced into the circuit when the receiver is taken from the hook. The curve Z represents the current in the ring ing'circuit when both the ringing machine and the source 60 are connected to the ringingcurrent. The curve W represents the flux in the relay S when both the ringing machine and the direct current are connected in the circuit.

In the embodiment shown a non-inductive shunt is placed across the terminals of the relay S in Fig. 1 and S, in F ig. 2. The relay S in Fig. 1 and S in Fig. 2 each fluctuates its armature in harmony with the ringing current, and when the armature is so fluctuated, the contacts controlled thereby will not be closed long enough to cause theactua tion of the relays controlled thereby. When, however, the current through S or S, is pulsating, as illustrated diagrammatically in Fig. 3, this pulsating current will, as eX- plained, cause the operation thereof and the tripping will occur. v

I have shown the theoretical diagram illustrated in Fig. 3 as being a mere theory as to what might take place under a given set of conditions, but I do not wish to be limited either to the embodiments illustrated in Fig. 1 and-Fig. 2, onto the theory of operationwhich I have illustrated in Fig. 3. In fact, I have illustrated these embodiments and this theoretical diagram in order to better explain my invention, and not that I may be limited thereto, as it will be apparent that many departures may be made from the modifications and the theory illustrated, especially when the claims are consulted.

1. In a. telephonesystem, the combination of a main station, a plurality of substations, telephone lines leading from the substations to the main station, substation apparatus at each substation including a bell and a switch, a ringing generator at the main sta' tion for supplying current to operate the bell, a ringing circuit including the ringing machine, thebell and the line to which'the bell is connected, means, subjected to fluctuating electrical currents when the subscribers bell is being rung, controlled by the sWitchat the substation for interrupting the ringing current when the subscriber responds, said means irresponsive to such fluctuating electrical currents and mechanism included in the ringing circuit responsive to fluctuating current governing said means when the subscriber responds to interrupt the ringing. l

2. In a telephone system, the combination of a main station, a substation, a telephone line connecting the substation to the main station, substation apparatus at thesubstation including a bell and a sWitch,a ringing circuit generator at the main station, a ringingcircuit including said generator, said bell and said telephone line, a relay at the main station irresponsive to fluctuating currents to which it is exposed during ringing controlling the ringing circuit, a circuit for said relay, a source of current in said circuit, a second relay responsive to fluctuating current connected in the ringing circuit controlling the circuit of the first named relay, a source of direct current in the ringing circuit and means in the ringing circuit to pre vent the flow of continuous direct current during the ringing, and means including the switch at the subscribers station for admitting the flow of direct current in the ringing circuit when the subscriber responds, whereby said firstand second named relays are operated and the ringing circuit generator automatically disconnected from the line.

In a telephone system, the'combination of a main station, a substation, a telephone.

line leading from the substation to the main station, substation apparatus including a bell and a switch controlled by the subscriber, a ringing generator at the main station, a ringing circuit including said ringing generator, said bell and the telephone line, a source of direct current in said ringing circuit, means in the ringing circuit during the ringing period preventing the flow of continuous current from said direct current source, means irresponsive to fluctuating current caused to flow therethrough during the ringing of the subscribers bell controlling said ringing circuit and mechanism in the ringing circuit responsive to fluctuating current controlling said last named means, the direct current excluding means being retired when the subscriber responds and operates the switch and said mechanism responding to the direct continuous current to cause the actuation of said ringing circuit controlling means to interrupt the same and disconnect the ringing machine from the bell.

4c. In a telephone system, the combination of a main station, a substation, a telephone line leading from the substation to the main station, substation apparatus including abell and a switch controlled by the subscriber, a ringing generator at the main station, a

ringing circuit including said ringing generator,1the telephone line and the bell, a source of direct current adapted to be connected in the circuit, a relay irresponsive to fluctuatingcurrents caused to flow there through during the ringing of the subscribers bellcontrolling the ringing circuit,

tory contacts for an appreciable length 01"? time, whereby the first named relay is operated and the ringing circuit interrupted.

5. In a telephone system, the combination of amain station, a substation, a telephone line leading from the substation to the main station, a signal device at the substation, means at the inn-in station for generating a fluctuating current to operate said signal device, a signaling circuit including said source of current, said signal device and the telephone .line, mechanism, at the main station irresponsive to such fluctuating current controlling said ringing circuit, a relay in the ringing circuit adapted to be operated during the ringing period to cause a fluctuating current to flow through said mechanism, said mechanism being responsive to a continuous flow of current, and means controlled by the subscriber and operated when he responds to-the call for causing said relay to cause a continuous flow of current through -said mechanism, whereby said mechanism interrupts the ringing circuit.

6. In a telephone system, the combination of a main station, a substation, a telephone line connecting the substation to the main station, substation apparatus including a signal device, current generating means for creatingcurrent to operate said signal de vice, a signaling circuit including said generating means and said device, mechanism including a switch having a vibratory contact controlling the signaling circuit and adapted to interrupt the same, said mechanism being irresponsivc to interrupt said signal circuit when said contact is vibrated, means in the ringing circuit for vibrating said contact during the ringing period, and means controlled by the subscriber for operating said means and causing it to close said switch for an appreciable length of time, whereby said mechanism is operated to interrupt the ringing circuit.

7. In a telephone system, the con1bina tion of a main station, a substation, a tele phone line connecting the substation and the main station, substation apparatus at the substation including a signal bell, a

ringing generator at the main station, a ringing circuit including the ringing generator, the telephone line and the signal bell, a relay controlling the ringing circuit and adapted when operated to interrupt the same, a circuit for the relay, a switch in the circuit, an electromagnct responsive to the ringing. current controlling the switch and adapted to vibrate the same when actuated by the ringing current, means to preventthe operation of the relay when said switch is vibrated by said elcctroniagnet during the ringing period and mechanism controlled by the subscriber and automatically operated when the subscriber responds for causing said elcctromagnet to maintain the switch closed for an appreciable period of time, said relay responding when said switch is closed, for an appreciable time, to interrupt the ringing circuit.

8. In a telephone systen'uthe combination of a main station, a plurality of substations, telephone lines leading from the substations to the main station, substation apparatus at each substation, including a bell and a switch, a ringing generator at the main station for supplying current to operate the bell, a ringing circuit including the ringing machine, the bell and the line to which the bell is connected, means subjected to fluctuating electrical currents when the subscribers bell is being rung controlled by the switch at thesubstation for interrupting the ringing current when the-subscriber responds, such means being irresponsive to such fluctuating electrical currents,a relay included in the ringing circuit responsive to fluctuating currents governing said means and a non-inductive shunt of said relay, said relay adapted when the subscriber responds to cause the actuation of the means to trip the ringing current.

9. In a telephone system, the combination of a main station, a substation, a telephone line leading from the substation to the main station, substation apparatus at the substation including a signalbell and a switch, a

riiigingniacliiiie atthe mainstation adapted to produce current to operate the signal hell, conductorsifor connecting the ringing machine .to a telephone line, a relay in said ringing circuit, a second relay controlling the ringing circuit,-a circuit for the second relay controlled 'bythe first named relay, said first named relay normallyresponding to ringing current but being ,lIIBSPOIISlVG to. the ringing currents to cause the o ieration of the second named' relay while theqsubstation talking bridge is open, and means controlled by the switch at the-substation foi changing the character of the current flowing I through the first named relay to cause the actuation of the second named relay.

10. In a telephone system, the combination oita ringing circuit including a source of ringing on "rent and a subscribers set, a relay controlling said circuit, a second relay adapt-ed whenoperated by pulsating current to cause the first named relay to interrupt the ringing circuit, the imagl'iet of the second relay causing its armature to fluctuate functionally to the frequency of the ringing current, butnot to causethe operation of the first-namedyrela-y when so operated, and means controlled by the sub scriber to-cause pulsating current to llow through the magnet of the second-named relay when the subscriber responds. 7

11. In a telephone system of theclass described, wherein the subscriber is rung automatically, the combination ofmeans for tripping said automatic ringing mechanism operating functionally to the frequency of the fluctuating ringing current, but when so operating being unable to trip said mechanism, means controlled by the subscriber and automatically operated when the subscriber responds to cause pulsating current to flow through said means and trip said mechanism. thereby interrupting the ringing.

In witness whereof, Ihave signed my name in the presence of two witnesses this 7th dav of November, 1914-. V

FRANK M. SLOUGH' Witnesses GEO. E. ROBERTS, JOHN PnLnssoN.

Copies of this patent may he obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

